Four rounds, CEO praise, then 'you were the runner-up'

A candidate cleared four interview rounds at a company switching to a new system that matched their exact skillset. The final round was with the CEO, who told them no applicant had ever made it past the first round before, and spent the hour describing what their day-to-day would look like. A thank-you email received an enthusiastic reply. Days later, a rejection arrived: they had chosen someone with "slightly more experience." The recruiter called them the runner-up.